Armyworms are destroying pastures across large parts of Gippsland.
Murray Goulburn agronomist Scott Travers said the area from Woodside to Buffalo was under heavy attack from the caterpillars.
Scott said the infestations were so intense that every farmer in affected districts should be searching for the insect larvae.
Armyworm caterpillars are smooth-bodied and have three white or creamy-coloured stripes running down their back and sides. Caterpillars can grow to about 30–40mm in length.
During the day, look under dead leaf litter at the base of the crop or pasture sward. At dusk or night, a torch should show them up on the leaves.